CN102003701B - Low NOx coal dust combustion method and device based on underfire air and overfire air - Google Patents
Low NOx coal dust combustion method and device based on underfire air and overfire air Download PDFInfo
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- CN102003701B CN102003701B CN 201010558131 CN201010558131A CN102003701B CN 102003701 B CN102003701 B CN 102003701B CN 201010558131 CN201010558131 CN 201010558131 CN 201010558131 A CN201010558131 A CN 201010558131A CN 102003701 B CN102003701 B CN 102003701B
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Abstract
The invention relates to a combustion improvement technology of an industrial fire coal boiler, aiming to provide a low NOx coal dust combustion method and device based on underfire air and overfire air. The method comprises: injecting parts of two-strand air required for combustion into a hearth from a boiler bottom ash hopper; strongly mixing with aslant downward injected fuel jet flow; fully utilizing the space of the bottom ash hopper to prolong smoke dwell time; burning fuel in a low-temperature oxidation zone; preventing volatile components from converting to nitric oxide; upwards and aslant injecting upper-layer fuel to form a reducing zone, so as to reduce generated nitric oxide into N2; and lowering nitric oxide emission amount. The invention also provides a boiler device for realizing the method. Under the condition that the original combustion condition is not influenced essentially, the invention effectively lowers the emission of nitric oxide and is easy to reform the existing boiler.
Description
Technical field
The present invention relates to the combustion modifications technology of coal-burned industrial boiler, relate in particular to a kind of low-NOx coal powder method, and realize the device of this method based on fiery leeward and after-flame wind.
Background technology
Nitrogen oxide NO
x(NO, NO
2, N
2O) be one of primary pollution source of causing atmosphere pollution.NO can destroy human body hemoglobin and cause anoxic, also has carcinogenesis, and the ozone in it and the stratosphere reacts and damages the ozone layer, and can is NO by the oxygen eremacausis also
2NO, NO
2Be acid contaminant, except that causing the acid rain acid mist, can also under of the effect of near-earth atmosphere, produce with hydrocarbon to human body and the bigger photochemical fog of environmental hazard at light.The burning of fossil fuel is one of important source of nitrogen oxide.70% was coal during the energy resource structure of China was formed, and the burning of coal will produce a large amount of NO
xThe environmental regulation of increasingly stringent requires the advanced NO of research and development
xEmission-reduction technology control NO
xEmission source is the NO of coal-burned industrial boiler especially
xDischarge capacity.
Existing low NO
xEmission control technique mainly can be divided into two types: low NO
xCombustion technology and gas denitrifying technology.Low NO
xThe principle of combustion technology is basic identical: all be the classification realization NO through fuel or air
xControl.The fractional combustion of present domestic employing generally can make combustion flame elongate, and causes unburned carbon in flue dust to exceed standard, and the boiler economy is descended, even causes flying ash in electric power plant recycling difficulty and bring the stacking problem of flying dust.For new power plant construction, can when design, increase furnace height, the prolongation time of staying of pulverized coal particle in stove solved the problems referred to above, and the combustion space increase also helps NO
xControl.But enlarge combustion space and must increase the boiler manufacturing cost.Gas denitrifying technology is mainly used and is comprised SCR (SCR) and SNCR (SNCR).Though SCR technology technology maturation, denitration efficiency can reach more than 90%, its shortcoming be take up an area of big, system complex, initial cost is big, operating cost is too high, and has the escaping of ammonia problem, is not suitable for China's actual conditions.Though SNCR technology initial cost is low, technology is simple, its maximum defective is exactly that the denitration rate only has 30%～50%, and its same the escaping of ammonia that exists with the SCR technology causes secondary pollution problem.
Summary of the invention
The technical problem that the present invention will solve is; Overcome deficiency of the prior art; A kind of low-NOx coal powder method and apparatus based on fiery leeward and after-flame wind is provided; Thereby through directly utilizing the boiler coal dust burning, do not influencing the original efficiency of combustion of boiler, boiler performance, do not increasing under the prerequisite of combustion space, realizing the ultralow NO of station boiler
xDischarging guarantees that simultaneously unburned carbon in flue dust does not increase.
The present invention is for solving the problems of the technologies described above, and the technical scheme that is provided comprises:
A kind of low-NOx coal powder method based on fiery leeward and after-flame wind is provided: be followed successively by low-temperature oxidation district, the reducing zone at the initial stage of catching fire, later stage reducing zone and burning-out zone in the boiler furnace from the bottom up;
The coal dust that acts as a fuel is accounted for 70%～80% main fuel and 20%～30% upper strata fuel in accounting for whole heat output of fuel ratios, being divided into; Wherein, (fuel pyrolysis under reducing atmosphere has suppressed volatile matter NO to the oblique reducing zone that sprays into down the initial stage of catching fire of main fuel
xFormation), upper strata fuel sprays into the later stage reducing zone obliquely, forms the NO that the reducing atmosphere reduction has generated at excess air coefficient α under less than 1 condition
xExcess air coefficient is less than 1 in the later stage reducing zone, and secondary wind gets into burning-out zone;
The fuel combustion required air quantity is divided into and accounts for 20%～40% fiery leeward and 20%～30% after-flame wind by accounting for air quantity, and surplus is a wind of secondary wind and pulverized coal conveying; Its moderate heat leeward is divided into two strands, sprays into burner hearth from the furnace hopper slope and the furnace hopper top of boiler respectively, forms two vertical symmetry vortexs in the low-temperature oxidation district, and excess air coefficient is 1.0～1.1 in this zone; (at this moment, fiery leeward and fuel jet intense mixing have reduced ignition temperature, control main fuel combustion process NO
xFormation, and the space of boiler furnace hopper made full use of, prolonged the time of staying of coal dust in stove.) upper end of after-flame wind fuel ejection position on the upper strata sprays into, and impels the residual coke after-flame behind the coal dust firing.
Among the present invention, when said upper strata fuel sprayed in the stove, the temperature at its spout place was in 1200～1600 ℃ of scopes.
Among the present invention, in order to improve the removal efficiency of nitrogen oxide (NOx), the excess air coefficient α in the later stage reducing zone is 0.8～1.0, and the time of staying is no less than 0.4s; In order to guarantee the burn-off rate of coke, the excess air coefficient α of burning-out zone is 1.15～1.25, and the time of staying is no less than 1s.
Further; The present invention also provides the device that is used to realize preceding method; Comprise boiler furnace and the furnace hopper, the burner that are installed in the body of heater, the combustion case of based on fuel is divided into low-temperature oxidation district, the reducing zone at the initial stage of catching fire, later stage reducing zone and four zones of burning-out zone from the bottom up successively with burner hearth; Said burner comprises from bottom to up each spout of layered arrangement successively: wind snout, 2～3 main fuel spouts, 1～2 upper strata fuel nozzle ports, 3～4 overfire air ports and 1～2 after-flame wind snout under 1～2 fire; Wherein, the fire setting angle of wind snout down is 0～30 ° of a updip, and the setting angle of main fuel spout is for having a down dip 0～30 °, and the setting angle of upper strata fuel nozzle ports is 0～30 ° of a updip, and the setting angle of after-flame wind snout is for having a down dip 0 °～30 °; Said setting angle updip or the have a down dip center line that all refers to spout and the angle between the horizontal line.Each spout height carries out reasonable Arrangement according to usual way and gets final product then according to the boiler furnace actual conditions.Wherein, wind snout is positioned at the slope or the top of furnace hopper under the fire, and the main fuel spout is positioned at the reducing zone at the initial stage of catching fire, and the upper strata fuel nozzle ports is positioned at the later stage reducing zone, and overfire air port is positioned at burning-out zone, and the after-flame wind snout is positioned at the upper end of upper strata fuel nozzle ports.
In technique scheme, said main fuel and upper strata fuel are coal dust, need not through special processed, or adopt other fuel.
The advantage that the present invention and prior art comparison are had is:
1, directly utilize boiler fired coal, do not influencing basically under the condition of boiler combustion, can be with NO
xDischarge capacity is reduced to 400mg/Nm
3Below.
2, use and should technology be transformed by the tangential firing Industrial Boiler, unburned carbon in flue dust is not higher than 14%.
3, be easy to existing boiler is transformed, need not to increase combustion space, only need transform burner; Introduce the part secondary wind at boiler furnace hopper place; The space of boiler furnace hopper is made full use of, prolonged the time of staying of coal dust in stove, and will have the burner nozzle angle now and make corresponding adjustment; Can realize corresponding environmental requirement, basically all very suitable for move burning smoke coal, boiler using brown coal at present.
4, this technology is convenient and easy on the implementation, and is reliable and do not increase the operation amount.
Description of drawings
Fig. 1 is a technical schematic diagram of the present invention.
Reference numeral among the figure is: low-temperature oxidation district 1, the reducing zone at the initial stage of catching fire 2, later stage reducing zone 3, burning-out zone 4, fiery leeward jet 5, main fuel jet 6, upper strata fuel jet 7, after-flame wind jet 8 and furnace hopper 9.
The specific embodiment
Below in conjunction with accompanying drawing and embodiment the present invention is done further explain.
Low-NOx coal powder method based on fiery leeward and after-flame wind is implemented on the Industrial Boiler main burner of power station, and is as shown in Figure 1.Boiler after the improvement is divided into low-temperature oxidation district 1, the reducing zone at the initial stage of catching fire 2, later stage reducing zone 3 and burning-out zone 4 four parts to burner hearth from the bottom up according to this.
In the application process, take the method for following reduction nitrogen oxide:
(1) account for the main fuel 6 of whole heat output of fuel 70%～80% and spray into burner hearth under oblique, fuel pyrolysis under the reducing atmosphere of initial stage reducing zone 2 of catching fire has suppressed volatile matter NO
xFormation;
(2) with 20%～40% hot blast as fiery leeward, divide two stocks not spray into burner hearth from boiler furnace hopper 9 slopes and furnace hopper 9 tops, form two vertical symmetry vortexs in furnace hopper 9 zones; Be under 1.0～1.1 the condition at excess air coefficient; Fire leeward 5 and main fuel jet 6 intense mixing have reduced ignition temperature, the formation of control main fuel combustion process NOx; And the space of boiler furnace hopper 9 is made full use of, prolonged the time of staying of coal dust in stove;
(3) all the other fuel of 20%～30% are sprayed into burner hearth obliquely as upper strata fuel 7 and form reproducibility district 3 under less than 1 condition, the NO that has generated at excess air coefficient α
xBe reduced to N
2
(4) add after-flame wind jet 8 at burning-out zone 4, excess air coefficient returns to normal value 1.15～1.25, and imperfect combustion product is fully burnt, to guarantee the after-flame effect.
After method of the present invention and the device practical application, not only can effectively reduce discharged nitrous oxides 40～60%, easy operating and control do not increase the operation amount.And existing boiler only needed appropriate reconstruction or install necessary nozzle, spout additional, almost do not have extra operating cost, so this method and device thereof have application and popularization value widely.
In a specific embodiment of the present invention; Account for whole heat output of fuel ratios: main fuel is 80%; Upper strata fuel is 20%; Upper strata fuel jet 7 jet opening distance main fuel jets 6 spouts tops 1.0m eminence sprays into, and the furnace wall center sprays into burner hearth to after-flame wind jet 8 from the four sides at the 2.4m place above upper strata fuel jet 7 spouts; Later stage reducing zone 3 is 1.05 with the excess air coefficient α of lower area, and the excess air coefficient of later stage reducing zone 3 is 0.8; The temperature at upper strata fuel jet 7 spout places is 1350 ℃, and the time of staying of upper strata fuel in later stage reducing zone 3 is 0.5s; The NOx discharge capacity is by the 670mg/m of blank test
3Reduce to 344mg/m
3, the NOx removal efficiency reaches 48%, and unburned carbon in flue dust is 11%.
At last, it should be noted that above what enumerate only is specific embodiment of the present invention.Obviously, the invention is not restricted to above embodiment, many distortion can also be arranged.The present invention can summarize with other the concrete form without prejudice to spirit of the present invention and principal character.Therefore; No matter from which point, above-mentioned implementations of the present invention all can only be thought can not limit the present invention to explanation of the present invention, and claims have been pointed out scope of the present invention; And scope of the present invention is not pointed out in above-mentioned explanation; Therefore, in implication suitable and any change in the scope, all should think to be included in the scope of claims with claims of the present invention.
Claims (5)
1. based on the low-NOx coal powder method of fiery leeward and after-flame wind, it is characterized in that:
Be followed successively by low-temperature oxidation district, the reducing zone at the initial stage of catching fire, later stage reducing zone and burning-out zone in the boiler furnace from the bottom up;
With the coal dust that acts as a fuel in accounting for whole heat output of fuel ratios, be divided into the main fuel that accounts for 70%～80% and the upper strata fuel that accounts for 20%～30%; Wherein, the oblique reducing zone that sprays into the initial stage of catching fire down of main fuel, upper strata fuel sprays into the later stage reducing zone obliquely; Excess air coefficient is less than 1 in the later stage reducing zone, and secondary wind gets into burning-out zone;
The fuel combustion required air quantity is divided into and accounts for 20%～40% fiery leeward and 20%～30% after-flame wind by accounting for air quantity, and surplus is a wind of secondary wind and pulverized coal conveying; Its moderate heat leeward is divided into two strands, sprays into burner hearth from the furnace hopper slope of boiler, forms two vertical symmetry vortexs in the low-temperature oxidation district, and excess air coefficient is 1.0～1.1 in this zone; The upper end of after-flame wind fuel ejection position on the upper strata sprays into, and impels the residual coke after-flame behind the coal dust firing.
2. according to the said low-NOx coal powder method based on fiery leeward and after-flame wind of claim 1, it is characterized in that: when said upper strata fuel sprayed in the stove, the temperature at its spout place was in 1200 ℃～1600 ℃ scopes.
3. according to the said low-NOx coal powder method based on fiery leeward and after-flame wind of claim 1, it is characterized in that: the excess air coefficient α in the said later stage reducing zone is 0.8～1.0, and the time of staying is no less than 0.4s.
4. according to the said low-NOx coal powder method based on fiery leeward and after-flame wind of claim 1, it is characterized in that: the excess air coefficient α of said burning-out zone is 1.15～1.25, and the time of staying is no less than 1s.
5. device that is used to realize the said method of claim 1; Comprise boiler furnace and the furnace hopper, the burner that are installed in the body of heater, it is characterized in that: the combustion case based on fuel is divided into low-temperature oxidation district, the reducing zone at the initial stage of catching fire, later stage reducing zone and four zones of burning-out zone from the bottom up successively with burner hearth;
Said burner comprises from bottom to up each spout of layered arrangement successively: wind snout, 2～3 main fuel spouts, 1～2 upper strata fuel nozzle ports, 3～4 overfire air ports and 1～2 after-flame wind snout under 2 fire;
Wherein, the fire setting angle of wind snout down is 0 °～30 ° of updips, and the setting angle of main fuel spout is for having a down dip 0 °～30 °, and the setting angle of upper strata fuel nozzle ports is 0 °～30 ° of updips, and the setting angle of after-flame wind snout is for having a down dip 0 °～30 °; Said setting angle updip or the have a down dip center line that all refers to spout and the angle between the horizontal line.
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| CN 201010558131 CN102003701B (en) | 2010-11-23 | 2010-11-23 | Low NOx coal dust combustion method and device based on underfire air and overfire air |
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| CN 201010558131 CN102003701B (en) | 2010-11-23 | 2010-11-23 | Low NOx coal dust combustion method and device based on underfire air and overfire air |
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| CN102003701B true CN102003701B (en) | 2012-12-26 |
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| CN102721797B (en) * | 2011-09-22 | 2014-11-05 | 辽宁省电力有限公司 | Method for analysis of relevance between production of HCN/NH3 by anthracite pyrolysis and production of NOx by anthracite combustion in boiler |
| CN103062759B (en) * | 2013-01-25 | 2015-05-20 | 福建永恒能源管理有限公司 | Vertical boiler with powder burner at bottom |
| CN103604117B (en) * | 2013-11-04 | 2015-12-30 | 武汉和信益科技有限公司 | The efficient low nitrogen burning method of the multiple classification of CFBB and combustion system |
| CN103712202B (en) * | 2013-12-19 | 2017-01-25 | 江联重工集团股份有限公司 | Combustion method for spherical flame boiler employing low-nitrogen ultra-lean volatile coke powder particles |
| CN105841184A (en) * | 2016-05-05 | 2016-08-10 | 上海华之邦科技股份有限公司 | Fractional combustion combustion-complementary air low-nitrogen device of industrial boiler |
| CN107388221A (en) * | 2017-07-17 | 2017-11-24 | 四川竹根锅炉股份有限公司 | A kind of ultralow nitrogen condensation horizontal steam boiler of four backhauls |
| CN108036308B (en) * | 2017-11-22 | 2019-04-12 | 东方电气集团东方锅炉股份有限公司 | Reduce the air distribution method of boiler furnace outlet amount of nitrogen oxides and the boiler for coal dust firing |
| CN107940446B (en) * | 2017-12-08 | 2024-01-16 | 东方电气集团东方锅炉股份有限公司 | Large entrainment jet flow over-fire air system and jet method |
| CN108397767B (en) * | 2018-03-06 | 2020-09-01 | 浙江哲丰能源发展有限公司 | Low-bed-pressure low-air-volume combustion operation method for circulating fluidized bed boiler |
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